1. Field of the Invention
The present invention relates to a fundus camera for photographing a fundus of an eye to be examined.
2. Description of Related Art
As for fundus cameras, those of non-mydriasis type have been widely used to photograph a fundus with visible light while the fundus is observed in infrared light. Besides, there have also been known those fundus cameras loaded with an additional function of visible fluorescent photographing (fluorescein angiography) (with mydriatics).
Conventionally, this type of fundus camera switches between an optical path of an observation optical system (hereinafter, referred to simply as an observation optical path) and an optical path of a photographing optical system (hereinafter, referred to simply as a photographing optical path) by using a pop-up mirror. In addition, at the time of fluorescent photographing, with such a camera, an infrared transmission filter in an optical path of an illumination optical system (hereinafter, referred to simply as an illumination optical path) is removed from the illumination optical path, and an exciter filter for fluorescence excitation is inserted in the illumination optical path. Then, after an alignment is carried out with a fundus being observed in visible light, a barrier filter for fluorescent photographing is inserted in the photographing optical path.
In this type of fundus camera, however, it is required to execute operations such as driving a pop-up mirror or inserting an exciter filter and a barrier filter synchronously with the firing (lighting) of a flash lamp for photographing. Accordingly, a driving mechanism and a control sequence for those operations should be complicated, which may increase the possibility of causing troubles such as a breakdown due to linkages.
In addition, at the time of fluorescent photographing, it takes much time and trouble to photograph if the exciter filter and the barrier filter are successively inserted manually.
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a fundus camera capable of facilitating observation, color photographing, and fluorescent photographing without using any complicated structure.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, a fundus camera for photographing a fundus of an eye to be examined is provided with a first illumination optical system for illuminating the fundus of the eye with infrared illumination light for observation, a second illumination optical system for illuminating the fundus of the eye with visible illumination light for photographing, a photographing optical system for photographing an image of the fundus with the visible reflection light from the fundus, an observation optical system for observing the fundus in the infrared reflection light from the fundus, and a barrier filter for transmitting fluorescence from the fundus as well as for cutting off visible illumination light for fluorescence excitation which has been resulted from or transmitted by an exciter filter.
The first illumination optical system includes a first light source, and the second illumination optical system includes a second light source and the exciter filter for visible fluorescence excitation disposed in an optical path. The photographing optical system includes a photographing element. The observation optical system includes an optical path shared with the photographing optical system and an optical path branched from the optical path of the photographing optical system by a first wavelength-selecting mirror, which has a wavelength-selecting property of transmitting either the infrared wavelength range or the visible wavelength range and reflecting the other. The barrier filter is disposed at least in the optical path of the photographing optical system